Last update: August 18, 2017 1 A guide to identifying the Asian earthworms Amynthas agrestis, Amynthas tokioensis, and Metaphire hilgendorfi Chih-Han Chang Department of Environmental Science and Technology, University of Maryland, College Park, MD Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD E-mail: [email protected]Introduction This guide is designed to help both ecologists and the general public to distinguish Amynthas agrestis, Amynthas tokioensis, and Metaphire hilgendorfi: three frequently co-occurring species that has been invading Northeast and Southeast US. Since 2015, many invaded sites previous thought to have only A. agrestis or M. hilgendorfi ended up being found to contain at least two, usually all three species. The widespread co-occurrence is a big challenge to ecologists and land managers, and becomes a confounding factor in studies where species identification was not done with a reliable taxonomy reference provided or by experienced earthworm experts. Information contained in this guide is extracted from the following paper: ‘Chang, C.-H., Snyder, B., Szlavecz K. (2016) Asian pheretimoid earthworms in North America north of Mexico: An illustrated key to the genera Amynthas, Metaphire, Pithemera, and Polypheretima (Clitellata: Megascolecidae). Zootaxa 4179 (3), 495–529’. If you need to cite information in this article, please cite the paper directly.
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Last update: August 18, 2017
1
A guide to identifying the Asian earthworms Amynthas agrestis, Amynthas
tokioensis, and Metaphire hilgendorfi
Chih-Han Chang
Department of Environmental Science and Technology, University of Maryland, College Park, MD
Department of Earth and Planetary Sciences, Johns Hopkins University, Baltimore, MD
Functional group Epi-endogeic Epi-endogeic Epi-endogeic
Size* 70-160 mm by 5-8 mm 75-125 mm by 5-7 mm 109-170 mm by 6-8 mm
Segment numbers
63-110 84-102 98-118
Spermathecal
pores
Three pairs or fewer in
5/6/7/8
Two pairs or fewer in
6/7/8
Two pairs or fewer in
6/7/8
Pre-clitellar genital markings
Areas of epidermal modification on VII and/or VIII, occasionally on VI and IX, ventral, unpaired and median or symmatrically paired, forming setal gaps, epidermis finely wrinkled or crosshatched
Present or absent, when present, small, circular discs, paired in front of the setal line on VII and VIII, median to the spermathecal pores, some specimens with an additional disc right in front of the pore on VI and/or VII.
Unpaired, mid-ventral, pre-setal clusters of numerous small tubercles on VIII-IX, occasionally on VII, X, XI
Male pores Usually absent; when present, small, transversely slit-like.
Present or absent; when present, on a small porophore surrounded by a deep furrow
Usually absent; when present, in a copulatory pouch
Post-clitellar genital markings
Usually absent; when present, single large pad with a concaved center, pre-setal, median to
male pores
Present or absent; when present, small, circular discs, 1-3 on each side of XVIII, one sometimes on the porophore, two median or lateral to the
male porophore
Usually absent; when present, on XVII or XVIII, similar to those in the pre-clitellar region
Prostate glands Usually absent Present or absent Usually absent
Caeca Manicate Manicate Manicate
* Length by width. While the ranges of size are similar among the three species, A. tokioensis is generally considered a small species and is smaller than the other two species.